The invention relates generally to transparent nano-composite materials and their production. More specifically, the invention relates to the production and use of a substrate coated with a transparent, wear resistant coating, including, for example, structures suitable for use in windows for optically guided armaments.
Many modern armaments use optical guidance systems to acquire and intercept their targets. Such systems often use an optical tracking system based on receiving infrared energy, often in the mid-infrared region at wavelengths around three to five micrometers. Examples of such systems include air-to-air, heat-seeking guided missiles, and smart munitions such as guided bombs that track a target by laser back scatter. In all of these devices, it is necessary to protect the relatively fragile optical tracking systems from heat and impact events. Protection of the optics requires the use of a highly impact-resistant window that is suitably transparent in the mid infrared region.
Missile window and dome materials are subject to extreme conditions of sand erosion and water droplet impact. They must be able to withstand this erosion and mechanical loading while at the same time be highly transmitting to infrared radiation. Sapphire (a single crystal form of alpha aluminum oxide) is one of the most frequently used materials for this application, but it is susceptible to damage from these impact and erosion mechanisms, as are several other materials suitable for use in these applications.
Therefore there is a need for new material systems and designs that provide the required combination of impact and erosion resistance, mechanical strength, and transparency to infrared radiation.